WASHINGTON — Two leading Senate Republicans on Sunday threatened tough punitive action by Congress against Saudi Arabia, including a possible halt of military sales, if missing journalist Jamal Khashoggi was killed inside the Saudi Consulate in Istanbul.

As Saudi Arabia warned of possible economic retaliation of its own, Sens. Marco Rubio and Jeff Flake, members of the Foreign Relations Committee, said Congress was prepared to move quickly and firmly if President Donald Trump failed to adequately respond to the Oct. 2 disappearance of Khashoggi, a Washington Post contributor. Rubio said U.S.-Saudi relations may need to be “completely revised” and stressed the U.S. would lose credibility on human rights if the Trump administration remained silent.

He also urged Treasury Secretary Steven Mnuchin to skip a conference this week in Saudi Arabia.

“I don’t think any of our government officials should be going and pretending it’s business as usual until we know what’s happened here,” said Rubio, R-Fla.

White House economic adviser Larry Kudlow declined to speculate on what Trump might do, citing a “swift and transparent investigation” in the coming week. He also brushed aside the apparent threats from the oil-rich kingdom of economic retaliation if the U.S. were to impose strict measures and said Mnuchin intends to attend the Saudi conference to address terrorist financing. Those plans could change as details of the investigation become available, Kudlow said.

“We will take stern action with the Saudis if necessary,” he said. “The United States is the dominant energy player so we’re in pretty good shape, in my opinion, with our energy boom to cover any shortfalls. We’ll wait and see, but rest assured that when the president says we will take actions if we find out bad outcomes, he means it.”

Trump pledged unspecified “severe punishment” in a “60 Minutes” interview that aired Sunday should the U.S. determine Saudi involvement in the disappearance of Khashoggi, who had written columns critical of Saudi Crown Prince Mohammed bin Salman. But Trump has said he does not want to halt a proposed $110 billion arms sale to Saudi Arabia because, he maintained, it would harm U.S. manufacturers.

Rubio declined to rule out a halt to the arms sales, stressing the U.S. must send a message to repressive governments worldwide, from Russia to Syria and China.

“There’s not enough money in the world for us to buy back our credibility on human rights if we do not move forward and take swift action,” Rubio said. “Arms sales are important not because of the money but because it also provides leverage over their future behavior.”

Flake said if the Saudis did, in fact, kill Khashoggi, Congress specifically might curtail U.S. military aid to Saudi-led forces in Yemen. Saudi Arabia is leading a coalition of Gulf states in a military campaign against Iranian-backed Houthi rebels in Yemen.

The U.S. provides weaponry, intelligence and logistical support for the bombing campaign.

“I do think that arms sales will be affected. Certainly our involvement in Yemen with Saudi Arabia will be affected,” said Flake, R-Ariz.

More than 20 Republican and Democratic senators instructed Trump last week to order an investigation into Khashoggi’s disappearance under legislation that authorizes sanctions for perpetrators of extrajudicial killings, torture or other gross human rights violations. The writer had been living in self-exile in Virginia for the last year. The lawmakers’ letter was a preliminary step under the Global Magnitsky Act toward taking punitive action.

Sen. Bob Corker, R-Tenn., who as chairman of the Senate Foreign Relations Committee has reviewed the U.S. intelligence into what happened to Khashoggi, has said, “The likelihood is he was killed on the day he walked into the consulate.”

Turkish officials say they fear Saudi agents killed and dismembered Khashoggi after he entered the consulate and that they have audio and video recordings of it. The kingdom has called the allegations “baseless” but has offered no evidence the writer left the consulate.

Trump visited the kingdom on his first overseas trip as president and has touted arms sales to Saudi Arabia.

Prodded Saturday to specify what type of “severe punishment” he could impose, Trump demurred.

“Well, there are many things we can do. Would you like to speak up about that?” he said, turning to Sen. James Lankford, R-Okla., who was at the White House for the arrival of American pastor Andrew Brunson, who was released from Turkey after nearly two years of confinement. “I don’t want to put you on the spot, but if you guys would like to tell them some of the many things we can do. There’s a big list.”

Lankford responded: “Yeah, there’s a big list. Obviously, we have a long-standing partnership with Saudi Arabia in a lot of areas.”

He added, “Let’s find out what did happen first.”